In my opinion Star Wars Republic Commando has to be one of the best first-person shooters made to date. This is because:
1. The combat feels great! running at a group of droids firing away at you with just the right amount of accuracy to be a threat and then dispatching them one by one with your wristblade is one of the best experiences in gaming!
2. The Team. Your team is made up of 4 people (no spoilers, as you find this all out in the opening) you, the elite Delta 38, the sniper Sev (Delta 07), the hot headed demolitions expert scorch (Delta 62), and the trustworthy commando fixer (Delta 40). Your command over them is relatively limited as you only have 4 options, Search and destroy, Form up, Stay here and Do thing (sniper point, grenade point, breach door, hack, etc) Also if you "die" your squad will carry on fighting until finished and then will revive you with half health (you can order them to revive you sooner but that often puts them in a very vulnerable spot).
3.The environments, without spoiling the game for you the envoronments range from full on battles with other troopers present to creepy environments with your enemies lurking around every other corner.
4. The story. The story really attaches you mentally to your squad and by the end you'll be scolding scorch for shooting you in the back rather than cursing the AI, and there are some real moments of accomplishment in the story such as the end of the first "chapter". The ending is awesome too!.
So to sum up, GO BUY THIS GAME!